The Glasgow Naturalist (online 2012) Volume 25, Part 4. Xx-xx

Vegetation and ‘site florulas’ of islands in West Loch Roag, Outer

Paul A. Smith1 & Jim McIntosh2

1 128 Llancayo Street, Bargoed, Mid Glamorgan, CF81 8TP, UK 2 BSBI Scottish Officer, Royal Botanic Garden, Inverleith Row, Edinburgh, EH3 5LR

1E-mail: [email protected] 2E-mail: [email protected]

ABSTRACT Four small, uninhabited islands in West Loch Roag, a sea loch in the west of the island of Lewis, , were visited in early July 2008, two grazed – Flodaigh and , and two ungrazed – Bearasaigh and Seana Cnoc. The habitats present and the interesting species are discussed, and the limited floras (‘florulas’) of each island are described, with full species lists. The species recorded for Campaigh are compared with a visit to the same island 30 years earlier.

INTRODUCTION There are many small islands in Loch Roag, a series of sea lochs in the west of Lewis, Outer Hebrides at approx 58° 16'N 6° 54'W (NB14 on the British National Grid). In spite of the draw of islands for Fig. 1. Large Armeria maritima (thrift) tussocks on the visitors, they have only rarely been visited in the NW plateau of Bearasaigh. history of botanical recording in the Outer Hebrides, if at all. Currie (1981) reports a visit in 1977, when There are three broad communities on the four islands several islands were circumnavigated, but a landing visited. Much of the flatter surfaces of the tops is was made only on Campaigh (Campay), NB1442. A covered by a plantain sward, containing Plantago list of the plant species was made, and this gives us a coronopus, P. lanceolata and P. maritima (buck’s- baseline with which to compare. horn, ribwort and sea plantain respectively), and also On 3 July 2008 as part of recording for a projected with varying amounts of Armeria maritima and tetrad (2km×2km square) flora of the Outer Hebrides a grasses. On the sheep-grazed islands the sward is visit was made to several of the islands – Flodaigh grazed very short, but otherwise it grows into tussocks (NB1241), Bearasaigh (NB1243), Seana Cnoc (Old and forms a maritime peat. In this habitat there are also Hill) (NB1143) and Campaigh (NB1442). It proved occasional species such as Ophioglossum vulgatum impossible to land on two smaller islets, Hairsgeir (adder’s-tongue fern) (Flodaigh), and where there is no (NB14A) and Mas Sgeir (NB1443). grazing Silene uniflora (sea campion) (Bearasaigh and Seana Cnoc). Seana Cnoc has an area dominated by The islands and their vegetation Rumex acetosa (sheep’s sorrel) forming a turf. Two of the four islands visited, Flodaigh and The sides of the islands, whether steep cliffs or smaller, Campaigh are low-lying with relatively easy access, sloping rocks have a different community, with Aster and therefore used for sheep grazing. They have short, tripolium, Ligusticum scoticum (Scots lovage), Silene well-cropped turf, but there are a few refugia on less uniflora, and Tripleurospermum maritimum (sea sheep-friendly habitat (coast, rocks, pebbles) where mayweed). plants less tolerant of grazing (for example Aster Flodaigh and Bearasaigh both have small, permanently tripolium (sea aster) on Flodaigh) can grow. wet depressions. On Bearasaigh the edge of the Bearasaigh and Seana Cnoc, by contrast, have steep depression has Ophioglossum vulgatum, and on rocky sides; they are grazed, but only by geese (which Flodaigh there is a small amount of Apium inundatum in places make paths) and therefore at a much lower (lesser marshwort). Both these islands also have intensity than the sheep, and in consequence they have Ranunculus flammula (lesser spearwort) in the damp well-developed tussocks and hummocks, with some areas, but on Bearasaigh there is also the small variety Armeria maritima (thrift) tussocks becoming very large of this species with very round leaves, R. flammula ssp (Fig. 1). They also have much more cliff habitat and minimus which is characteristic of damp patches in therefore some different species. very exposed situations near the sea.

The most interesting species, abundant on all four of species could be added to his list, and although we the visited islands, was Lychnis flos-cuculi (ragged have made a nearly complete list, it is likely that a few robin), which was scattered throughout the turf. This is species still lurk undetected. a much shorter variety than the usual one of marshy The taxa recorded on 3 July 2008 are listed in Table 2, areas, with the flowers forming a dense cluster at the with a * denoting that they were also recorded by top of the short stem and with wide petals, and it is Currie unclear what the appropriate name for this variety is Nine species were recorded in 2008 but not seen during (although it may be forma pygmaea Ostenf., see Jonsell the visit in 1977; they are generally less conspicuous 2001, p178). It is known from other islands in the species such as the Euphrasia (eyebright) which was in (Heslop Harrison 1954, 1956). On small quantity as non-flowering plants, and Sagina Seana Cnoc there were two colour forms – most maritima (sea pearlwort) which is an annual of bare specimens the usual deep pink, with a few much paler peaty patches near the sea. The most obvious of the (but not quite white). species present in 2008 but not recorded in 1977 was The rocks round Flodaigh, Bearasaigh and Seana Cnoc Spergularia rubra (sand spurrey), which was abundant all have Aster tripolium (sea aster), as var condensatus, in barer patches at the western end of the island. It is a fleshy-leaved plant of rocky places which looks quite interesting to speculate that both the bare patches and different from the more usual var tripolium on salt presence of Spergularia are connected with the sheep marshes. On Flodaigh it occurs in small quantity, on grazing, although Currie noted grazing in 1977 too. coastal rocks where there is protection from grazing. Currie additionally recorded Aira praecox (early hair- On Bearasaigh the absence of sheep has allowed the grass), Asplenium marinum (sea spleenwort), Carex Aster to thrive away from the rocks, and it has panicea (carnation sedge), Festuca ovina (sheep’s colonised in bare peaty pools and hollows, so it is fescue) and Tripleurospermum maritimum. Any of common on the top of the islands as well as round their these could still be present and overlooked, but coasts. particularly Tripleurospermum is very obvious and it seems likely that this has declined. Site Floras The Botanical Society of the British Isles has been Site florula for Bearasaigh suggesting the concept of site floras, a description of Bearasaigh (Fig. 2) is a steep-sided island with cliffs the plants for relatively small, well-defined sites that most of the way round. Its summit is 58m, and the top can be visited regularly with a reasonable degree of of island forms a plateau, sloping down slightly to the coverage (Lockton 2007). It is generally difficult to north-west, sloping more steeply to around 30m in the define such sites in the Outer Hebrides away from east. Its longest axis runs roughly NW to SE, about habitation, but islands form natural sites, though with 400m long, and it is about 250m wide at its widest. small floras (‘florula’). They will generally be covered There is a stac to the SW, Stac an Tùill, but this was by only a single visit, but these visits are much more not visited. The underlying rock is gneiss (Fettes et al. likely to be recorded than visits to mainland sites of 1992). The NW part of the island consists of a tussocky comparable size. Since it is sensible to follow up maritime heath, with very large Armeria tussocks (Fig. existing site descriptions, we provide a site florula for 1), and a few boulders, many with temporary pools at Campaigh, and we also give initial descriptions for the their bases. The SE part is more grassy, with one other islands visited as a baseline for future visits. permanent pool. Summary information is given in Table 1.

Site florula for Campaigh Campaigh is approximately 500m long and 250m across at its widest, and rises to just over 30m above sea level at its highest. It runs roughly from SW to NE, with the SW end being lower and shelving to low rocky sides; the NE end is separated from the rest of the island by a natural arch, and has some cliffs. The underlying rock is gneiss (Fettes et al. 1992), although the arch is presumably formed by erosion of a softer dyke. The island is turf-covered away from the rocky and cliffy edges, and grazed throughout by sheep. The Fig. 2. Bearasaigh looking at the NW end, with Stac an cliff parts are used by nesting seabirds, and there is Tùill to the right, and Flodaigh the lower island behind some evidence of eutrophication from their use of the the Stac. island. There is no standing water. A list was published for Campaigh by Currie (1981) Bearasaigh was visited on 3 July 2008 for 1½ hours; from a visit of “an hour or two” on the evening of 23 coverage was good at the western end where we June 1977, apparently for bird counting as well as landed, but more rushed at the eastern end, and it is botany. The authors of the present paper visited for one likely that additional searching will turn up a few extra hour on 3 July 2008, a very similar time of the year to species here too. 49 taxa were recorded (see Table 2) the previous visit, and our attentions were more exclusively botanical. Currie commented that some

Maximum Dimensions Approx Time spent Taxon Taxa Island (length × area recording Grazing density recorded breadth × (ha) (hrs) (taxa ha-1) height) (m) geese Bearasaigh 400 × 250 × 58 9.8 1½ 49 5.0 (v light grazing) sheep Campaigh 500 × 250 × 30 10.2 1 34 3.3 (heavy grazing) sheep Flodaigh 450 × 400 × 22 18.6 ¾ 66 3.5 (heavy grazing) geese Seana Cnoc 600 × 300 × 90 11.1 1¼ 28 2.5 (v light grazing)

Table 1. Summary information on islands visited on 3 July 2008.

Site florula for Seana Cnoc We had a short visit of only ¾ hour to Flodaigh on 3 Seana Cnoc (Fig. 3) is another steep-sided island, July 2009. This was therefore the least well covered of basically a long ridge running almost E to W, its edges the islands discussed here, with nearly all the effort on a combination of cliffs and very steep vegetated slopes. the eastern part, and it is likely that several additions It is about 600m long, and 300m wide and is the tallest could be made to the species list with a longer visit. of the islands visited, with a summit just over 90m. The Nevertheless it had the greatest diversity of the islands underlying rock is gneiss (Fettes et al. 1992). Seana visited, with 66 taxa recorded (see Table 2). Cnoc is a dry island without standing water, and without the peaty pools found on Bearasaigh. It is DISCUSSION predominantly grassy with a mainly Festuca rubra (red The limited number of habitats on small islands means fescue) turf, with abundant Lychnis flos-cuculi and that the numbers of species found was small relative to Silene uniflora. the main islands of the Outer Hebrides. 20 species were common to all four islands, all of them common and widespread in exposed coastal habitats in the Outer Hebrides. Additional species are found according to the different habitats present, and presumably their occurrence is also affected by how easily seeds can reach isolated islands. Some species are likely to have come in with sheep as they are moved to and from the grazed islands, and Spergularia rubra may be an example of this type of translocation.

ACKNOWLEDGEMENTS We are grateful to Murray and Hannah of Sea Trek for

their skill in getting us on and off the islands, and to Fig. 3. Seana Cnoc, looking at the South side. Mila Teneva and Simon Drysdale for joining us in

island-hopping. Seana Cnoc was visited on 3 July for 1¼ hours. Since the variety of habitats was smaller than on the other islands visited, it is likely that a reasonably comprehensive list was obtained. 28 taxa were recorded (see Table 2).

Site florula for Flodaigh Flodaigh (Fig. 2) is a low-lying, sheep-grazed island, with a variety of habitats. It has an irregular outline with several geos, and at its largest is about 450m long and 400m wide. The bay on the south side that faces the islet of Tamna was formed by a pebble beach, partly vegetated, and there was a small permanent pool in the peatier ground some way to the north of this.

Much of the turf was damp and peaty. The underlying rock is gneiss (Fettes et al. 1992).

Species Campaigh Bearasaigh Seana Cnoc Flodaigh Agrostis stolonifera *    Aira praecox   Alopecurus geniculatus  Anagallis tenella  Angelica sylvestris  Anthoxanthum odoratum  Apium inundatum  Armeria maritima *    Aster tripolium var condensatus    Atriplex sp. *    Bellis perennis  Callitriche sp.  Calluna vulgaris  Cardamine pratensis  Carex flacca   C. nigra    C. ovalis  C. viridula ssp oedocarpa  C. viridula ssp viridula *   Cerastium diffusum  Cerastium fontanum *    Cirsium vulgare  Cochlearia officinalis s.l. *    Dactylorhiza maculata   Dactylis glomerata  Danthonia decumbens   Deschampsia cespitosa  Eleocharis palustris  Empetrum nigrum  Erica cinerea  Eriophorum angustifolium   Euphrasia foulaensis  Euphrasia officinalis agg.    Festuca rubra s.l. *    Galium aparine  Glaux maritima *  Holcus lanatus *    Hydrocotyle vulgaris *   Juncus articulatus   Juncus bufonius s.s.    Juncus bulbosus  Leontodon autumnalis *   Leontodon autumnalis var autumnalis  Ligusticum scoticum    Lotus corniculatus *    Luzula multiflora ssp multiflora  Lychnis flos-cuculi *    Montia fontana ssp fontana   Nardus stricta  Ophioglossum vulgatum   Plantago coronopus *    Plantago lanceolata *    Plantago maritima *    Poa annua  Poa humilis *    Poa trivialis  Potentilla anserina  Potentilla erecta  Primula vulgaris  Prunella vulgaris   Puccinellia maritima     Ranunculus acris *   

Ranunculus ficaria ssp ficaria    Ranunculus flammula   Ranunculus flammula ssp minimus  Rumex acetosa *    Rumex crispus *   Sagina maritima  Sagina procumbens *    Sedum rosea   Selaginella selaginoides  Silene uniflora *    Spergularia rubra  Stellaria media *   Succisa pratensis   Thymus polytrichus *   Trifolium repens *    Triglochin maritimum  Tripleurospermum maritimum    Urtica dioica  Viola riviniana 

Table 2. Species recorded in the four islands on 3 July 2008; * denotes species also recorded for Campaigh by Currie (1981).

REFERENCES Currie, A. (1981). Vegetation on islands of West Loch Roag, Lewis. Hebridean Naturalist 5, 57-58. Fettes, D.J., Mendum, J.R., Smith, D.I. & Watson, J.V. (1992). Geology of the Outer Hebrides. Memoirs of the British Geological Survey Sheet (solid edition) Lewis & Harris. Heslop Harrison, J.W. (1954). Botanical investigations in the Isles of Lewis, Harris, , Coppay, and in 1953. Proceedings of the University of Durham Philosophical Society 11, 135-142. Heslop Harrison, J.W. (1956). Botanizing in the Outer Hebrides in 1955 and 1956. Proceedings of the University of Durham Philosophical Society 12, 141-149. Jonsell, B. (ed.) (2001). Flora Nordica 2. Bergius Foundation, Stockholm. Lockton, A. (2007). Coordinator’s corner: site surveys. BSBI News 104, 79.